Those wacky MIT students are at it again. From 2.009 Product Engineering Processes: Archimedes:
Ancient Greek and Roman historians recorded that during the siege of Syracuse in 212 BC, Archimedes (a notably smart person) constructed a burning glass to set the Roman warships, anchored within bow and arrow range, afire. The story has been much debated and oft dismissed as myth.TV’s MythBusters were not able to replicate the feat and “busted” the myth.
Intrigued by the idea and an intuitive belief that it could work, MIT’s 2.009ers decided to apply the early product development sketch or soft modeling process to the problem.
Jumping ahead, you can see that 2.009 came to a different conclusion…
Here’s what the kwc blog had to say about MythBuster’s experience (in episode 16):
The first myth was advertised as the oldest myth they’ve ever busted, going back all the way to the 3rd century BC and Archimedes. I didn’t really know that much about Archimedes beyond his buoyancy principle, but, as I found out, he was a great mathematician and inventor of the catapult, lever, and compound pulley (block and tackle). One of his attributed inventions, though, is considered a little more dubious.As the myth has it, during the Second Punic Wars, Archimedes built his ‘burning mirrors,’ which was an arrangement of mirrors that was capable of focusing a ray of sunshine on approaching ships and setting them aflame.
After testing bronze and various other reflective materials, Adam settled on making a 400 sq ft mirror using 300 individual mirrors arranged in a circular configuration, with all of the mirrors focused on the same point at a 60 ft distance. Apparently, mirrors can put out 30kW/sq ft, which means that their mirror could theoretically put out about 600 degrees of heat.
Adam had some of the new crew build half a trireme, which they had an interesting time balancing in the water. With their giant mirror raised, they were able to bring up the temperature to 200 degrees. The crew raised some additional sheets of reflective material, but was only able to get the temperature up to 280 degrees. Jamie was even able to stand directly in the beam, as the mirrors simply weren’t focused enough.
The mirror met a fateful end dropped onto the pavement, and the boat met a similar fate as they were unable to burn it to ash using flaming arrows and Molotov cocktails. busted
There’s actually a guy on the net who has built his own solar death ray, and he has an entire gallery of burned and molten targets.